&NA;Computed tomography (CT) was used in place of contrast enemas as the initial imaging study to evaluate patients with the clinical diagnosis of acute sigmoid diverticulitis. This report attempts to clarify the role of CT in the management of acute sigmoid diverticulitis by reviewing its usefulness in the diagnosis and treatment of 59 patients. CT established that three patients (5 percent) were hospitalized with an incorrect clinical diagnosis. Thirty‐seven patients (62.7 percent) were identified as having uncomplicated acute diverticulitis. These patients were all treated successfully with nonsurgical therapies and were discharged in an average of 6.8 days. In the remaining 19 patients (32.2 percent), CT revealed complicated acute diverticulitis by identifying abscess, fistula, peritonitis, or obstruction. Eleven of these 19 patients required urgent surgery or CT‐guided percutaneous drainage of an abscess. The four patients whose abscesses were drained percutaneously responded favorably and underwent an elective single‐stage resection. The average hospital stay for patients with complicated diverticulitis was 13.6 days. Computed tomography is a useful aid in the initial management of patients with acute diverticulitis. It is a noninvasive test that recognizes and stratifies patients according to the severity of their disease. It has the further advantage of providing information about extracolonic pathology and anatomic variation useful for surgical planning. Additionally, early CT‐guided needle drainage allowed downstaging of complicated diverticulitis, avoided emergent surgery, and permitted single‐stage elective surgical resection.